Annoying buzz sound

[vothros]

Hello! Merry Christmas and a Happy New Year!

I have a little annoying problem with my pc.
It does a buzz sound with tempo, and after 10-15 minutes it stops. Usually it does it when i open my pc and load many programs (steam,skype,mozilla with many tabs etc).
It used to do it since i bought it, it was not so annoying. I thought to update the bios in case it's a motherboard matter, still continued to do it and even louder.
I opened the case to see where this buzz comes from but i cannot understand exactly. My mind goes to cpu or ram or cooler of cpu but i am not so sure. I put my ear next to psu to understand, but it's hard to understand where it comes from.

My pc is:
Mobo: GA-990FXA-UD3 (rev. 1.0 - F9 Bios)     http://www.gigabyte.com/products/product-page.aspx?pid=3894#ov
CPU:   AMD Phenom II X6 1090T 3.2 GHz Six Core Socket AM3 125W Box Black Edition (HDT90ZFBGRBOX)
Cooler CPU:  Corsair Air Series A70              http://www.corsair.com/en/air-series-a70.html
RAM:   Kingston Hyper X 16GB DDR3 Non ECC CL9 1600MHz (KHX1600C9D3K2/8GX)   http://www.kingston.com/datasheets/KHX1600C9D3K2_8GX.pdf
PSU:    Corsair TX850 V2                                http://www.corsair.com/us/power-supply-units/tx-series-power-supply-units/enthusiast-series-tx850-v2-80-plus-bronze-certified-850-watt-high-performance-power-supply.html
GPU: GeForce GTX 560 Ti Twin Frozr II OC

The only thing i thought of is maybe i should do some settings on Bios about ram voltage but i don't know anything about such settings neither i ever touched anything in Bios except of Boot Priority.

Some help would be appreciated,
thank you and sorry for my english.

[autotech]

It doesnt sound like a bios matter at all but a bad capacitior on the PSU pr MB. First do you have another pc to put your psu in and see if the noise moves with it and then try the viedo card it neither of them are it id start checking motherboard.

That psu is a pretty good one and has a long warranty on it.
Not sure about cooler but cpu is a good one. could be a fan wine the way to check that is when t is doing it stick a pencil in the fan to slow it down and stop it and see if the whine goes away.

[vothros]

Unfortunately i don't have a second pc to test my parts.

I checked the fans today with a pencil but it's not the  problem.
Keeps buzzing and after 10-15 minutes it stops. And here is the weird thing, when it stops it sounds like something is turned off.
So, when it is turned off and i keep using the pc, if i will start again opening many programs, it will start like something is turned on, pc hangs for 1 second or maybe less (!), and starts buzzing for 10-15 min.

It really started breaking my nerves because i don't know where it comes from.
Because of this "turned on - turned off" sound, i think it could be the cpu??? I hear a "click" (turns on) and starts buzzing. It does a "click" when it will stop buzzing (turns off).

Could it be cpu?? My mind goes there...but still cannot be sure 100%.

[autotech]

I highly doubt it is the cpu. Did you check your case fans and video card fan?  Could it be your hard drive it could whine and make your pc hang. Easy way to check hard drive is to unplug it when noise is being made then shut down computer b4 you plug it back it.  Without something to check parts in might be a good idea to take to a local shop and have them look at it.
When you are opening alot of programs you are acessing your hard drive and making it work harder.

[vothros]

Uuum.....unplugging the hard drive while is working, isn't it dangerous??

I bought it 1,5 year ago, i think all my parts are still in warranty, isn't it ? At least for mobo+psu+cpu+graphics card.

[autotech]

Depends how you bought it. HP, Dell and so on usually have a 1 year warranty if you built it urself then warranty is longer.  Unplugging hard drive while on isnt dangerous but plugging it in while on is. So you can unplug it while on if noise is still there hot the power button to turn of when it is off plug in hard drive.

[vothros]

I built it myself.

So, i unplugged one of the 3 hard drives i have (the latest one) and the buzzing sound got much more lower. I mean, there is one, but very very low.
Now that i put hard drive back on, annoying buzz sound is back again. 
So, i am thinking if it is the hard drive or something else cause there was a buzzing sound also, but in much more lower noise.
I think something is wrong with a capacitor or i know, maybe the cpu cooler, although it says it's quiet, or maybe the cpu.
I will call the shop where i bought it to talk with the technician.
Thanks for your help

[autotech]

you are on the right path then and you welcome.

[Ripshod]

If I'm on the wrong track ignore this post.

Are you sure the buzz is not coming from your speakers? Reason I ask is I had the buzz from my onboard audio running a nVidia 660ti with a TX850 that was failing. Ripple on one of the PSU outputs.
Replaced the PSU and all was quiet.
Also remember a case of buzz that was cured by disconnecting the front panel audio from the motherboard - apparently the cable itself was picking up RFI from the GPU and feeding it back into the motherboard's audio circuits.

I may be off-beat but it makes sense.

[vothros]

Well, i am sure it's not from the speakers cause i don't use the onboard soundcard, i have pci soundcard, almost 10 years, and i am sure it's working perfectly.

I think it's something between cpu-cpu cooler and motherboard, because of the sound that makes when it starts or stops (it's like a "click-switch" sound that turns on/off and after this "click" sound starts buzzing or stops buzzing).

[Ripshod]

You stopped the cpu cooler's fan  and it carried on. Bear with meon this one:

PWM is not a DC signal, it's a signal that rises to full voltage then back down to zero at a high frequency, within audible range. Stopping the fan won't necessarily stop the buzz cos the pwm signal will still make the fan's internals vibrate. It stops, you open programs increasing the load on the cpu, increasing the temp, thus increasing the fans speed via a stronger PWM signal.

I'm not that familiar with your motherboard but can you go into the bios. I'm working from my mobo's manual here, maybe a section 'PC Health Status', then maybe 'CPU Smart Fan Mode'. If it's 'PWM' or 'Auto' change it to 'Voltage', save and reboot. See how that goes, will eliminate the fan at least.